Technical Field
The present disclosure relates generally to ZPGM catalyst systems, and, more particularly, to a process to enhance the washcoat adhesion (WCA) on metallic substrates in ZPGM catalyst systems.
Background Information
Catalyst in catalytic converters may be manufactured to decrease pollution caused by exhaust gases from automobiles, utility plants, processing and manufacturing plants, trains, airplanes, mining equipment and other engine-equipped machinery. A major problem in the manufacturing of catalyst systems may be achieving the required adhesion of a washcoat to a substrate and/or adhesion of a washcoat to an overcoat.
The high porosity of the surface in ceramic substrates may provide a high degree of coating adhesion. This is not the case for the adhesion of coating to metallic substrates which may be affected by type of materials used and other factors. Factors that may affect adhesion include, but are not limited to, substrate geometry and size, substrate cell density, washcoat (WC) and overcoat (OC) particle size distribution, additive or dopant properties, amounts of WC and OC loadings, ratio of alumina to oxygen storage material (OSM), and treatment. To this end, there may be a need for improvements in the process of making a ZPGM catalyst system with lower loss of adhesion and improved catalyst performance.